Concept formation tasks with a set shifting component have proven sensitive to frontal lobe dysfunction. The Wisconsin Card Sort, perhaps the most widely known test of this class, activates prefrontal regions in most normal but no schizophrenic subjects. It is presented in the visual modality. To further validate the use of such a test and to facilitate cognitive activation in EEG - BEAM studies while reducing eye movement, an auditory analog of the card sort was developed.